In the field of inked ribbons, a supply spool and a take-up spool have been provided on opposite sides of a typing or printing station with means for reversing the direction of travel of the ribbon to obtain longer ribbon life. The inked ribbon has usually been made to travel along a line of printing wherein the spools are positioned beyond the ends of the printing line. However in the case of certain printers, a wide ribbon is used and is made to travel in a direction that is normal to the print line.
In the present day printers, it is common practice to use a ribbon cassette carrying an endless ribbon which is caused to be driven past the printing station with the ribbon being either a pre-inked ribbon or a ribbon which is to be continuously or frequently reinked during the printing operation. The ribbon cassette may be of the stuffing box type, wherein the ribbon is contained within the cassette in random manner and the ribbon is unfolded at the cassette exit and is caused to be driven past the printing station and then trained to enter the cassette to be folded in random manner therein. A ribbon may be utilized in a mobius loop configuration wherein the ribbon is in substantially continuous contact with an inking core or the ribbon may have a plurality of coils around a core for controlled inking thereof.
It is seen that the inked ribbon requires proper positioning and control in its path from the stuffed condition in the cavity of the cassette and through the exit port towards the printing station. The inked ribbon needs to pass freely through the exit port from the cavity and also be restrained in a manner to provide proper tautness of the ribbon past the printing station.
Representative prior art in ribbon cassettes is disclosed in U.S. Pat. No. 4,209,261, issued to D. W. Bell et al. on June 24, 1980, which shows a ribbon cassette having a dam over which the ribbon travels when exiting from the stuffing cavity.
U.S. Pat. No. 4,536,098, issued to B. P. Sheehan et al. on Aug. 20, 1985, discloses a ribbon cassette having a body portion with a dam in the cavity thereof and a cover with a dam opposite the cavity dam and wherein the ribbon passes between the dams.
U.S. Pat. No. 4,616,942, issued to H. Nagasawa et al. on Oct. 14, 1986, discloses a ribbon cassette having a dam portion over which the ribbon crosses when leaving the stuffing chamber.